A shoulder separation, or AC separation, is a very frequent injury among certain athletes.
In this injury the clavicle (collar bone) separates from the acromion (part of the shoulder blade). It is commonly caused by a fall directly on the “point” of the shoulder. This commonly occurs when football players are tackled, hockey players get checked into the boards, or mountain bikers go over their handlebars.
Most AC injuries don’t require surgery. Most patients recover with full function of the shoulder. Recovery can take a few days to 12 weeks depending on the severity of the separation. Disruption of the AC joint results in pain and weakness in the entire shoulder and arm. The pain is most severe when the patient attempts overhead movements or tries to sleep on the affected side.
It is important to note that surgery is recommended only due to severity of injury. Surgery will not get you back to normal faster in the case of mild injuries. Surgery is only beneficial when the injury is so severe that it would leave permanent disability. Most pro athletes are able to return to sport without surgery after a shoulder separation.
How do we know which AC injuries need surgery?
The severity of an acromioclavicular joint injury depends on which supporting structures are damaged, and the extent of that damage. Tearing of the acromioclavicular capsule alone is not a serious injury, but when the additional ligaments are ruptured the collarbone can become permanently unstable.
Simple AC injuries are classified in three grades ranging from a mild dislocation to a complete separation. AC Separations of Grade 1 through 3 will usually heal well without surgery, leaving minimal long-term problems.
- Grade 1 - A slight displacement of the joint. The acromioclavicular ligament may be stretched or partially torn. This is the most common type of injury to the AC joint.
- Grade 2 - A partial dislocation of the joint in which there may be some displacement that may only be seen on xray. The acromioclavicular ligament is completely torn, while the coracoclavicular ligaments remain intact.
- Grade 3 - A complete separation of the joint. The coracoclavicular ligaments and the capsule surrounding the joint are torn. Usually, a bump at the site of injury is obvious though a lot of that bump is blood and swelling from the injury. It will get smaller over time.
Complex AC separations are Grades 4 through 6 are very rare and are usually the result of a high-energy injury such as one that might occur in a motor vehicle accident. They are all treated surgically because of the severe disruption of all the ligamentous support for the arm and shoulder. They usually involve complete separation of the collarbone from the acromion, disruption of all the ligaments, and displacement of the clavicle into the surrounding muscles.
